Search publications of the members of the Royal Belgian institute of natural Sciences
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Conservation units based on mitochondrial and nuclear DNA variation among European bullhead populations ( Cottus gobio L ., 1758 ) from Flanders , Belgium
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Contribution to the systematics and zoogeography of the East-African Acomys spinosissimus Peters 1852 species complex and the description of two new species (Rodentia: Muridae)
- We revised the taxonomic status of the putative Acomys spinosissimus complex based on the comparative study of speci- men collections from Tanzania, Zambia, Zimbabwe, Mozambique, DR Congo and South Africa, by means of analysis of external morphology, craniometry, enzymes, mitochondrial DNA sequences and karyology. Our results confirm that A. spinosissimus represents a complex of species with seemingly non-overlapping distribution ranges. The distribution range of A. spinosissimus appears to be restricted between the Zambesi and Limpopo Rivers, while the reinstated A. selousi (that includes A. transvaalensis) occurs further to the South (i.e. northern limit seemingly just north of the Limpopo River). The investigated populations north of the Zambezi River are morphologically and genetically distinct from A. spinosissimus and A. selousi. Based on this evidence, we described Acomys muzei sp. nov. and Acomys ngurui sp. nov., each one occur- ring separately along one side of the Eastern Arc Mountains. Finally, we lacked sufficient information to describe a third new species from the area north of the Zambesi River.
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Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region.
- African mole-rats (Bathyergidae, Rodentia) of the (eu)social genus Fukomys are one of the most speciose mammal genera endemic to Sub-Saharan Africa. Fukomys distributed in the Zambezian phytochorion is characterized by extreme chromosomal variation (2n=40-78). We inferred a molecular phylogeny of Zambezian Fukomys to resolve the interrelationships and the evolutionary history of the known chromosomal races. We sequenced the entire cytochrome b gene (1140bp) for a total of 66 specimens representing 18 karyotypical races from Zambia. An additional 31 sequences were retrieved from GenBank including data on all other chromosomal races. The haplotypes belonging to a small chromosomal race from Salujinga cluster with the Fukomys mechowii (Giant mole-rat) haplotypes. Differential degrees of chromosomal variation are observed among the major mole-rat clades, which is most pertinent when comparing the central Zambezian Fukomys micklemi and the northern Zambezian Fukomys whytei clades. The karyotypically hyper-diverse (12 known chromosomal races) Fukomys micklemi clade shows low levels of cytochrome b sequence divergence. Within the F. whytei clade we find a more conservative pattern of chromosomal diversification (three known chromosomal races) while the levels of sequence divergence are much higher then in the F. micklemi clade. Our results suggest that chromosomal changes may drive phyletic divergence and, eventually, speciation. The observed cladogenetic events during the Plio-Pleistocene within the F. mechowii, F. whytei, F. damarensis and F. micklemi clades appear to coincide with climatically mediated speciation bursts in other savannah dwelling mammals, including hominids. Based on the molecular data presented, combined with morphological and chromosomal data, the taxonomic implication seems to be that Fukomys may contain several (undescribed) cryptic species.
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Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits.
- As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species.
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Discovery of a new duiker species (Bovidae: Cephalophinae) from the Dahomey Gap, West Africa
- Among the two most widely distributed duiker species, Philantomba monticola (Thunberg, 1789) and Philantomba maxwelli (C.H. Smith, 1827), the latter shows geographic variation in pelage color and body size. This issue was not investigated in detail so far, especially in the eastern region of its distribution area, notably due to the lack of material from the Dahomey Gap. We undertook a species-level revision of Philantomba in West Africa, notably including a series of specimens collected in Togo, Benin and Nigeria. Using morphological measurements (craniometry) and genetic data (two mitochondrial and three nuclear markers), we describe a new duiker species occurring in the Dahomey Gap (Togo, Benin) and the Niger delta, Philantomba walteri sp. nov. This discovery highlights the importance of the Dahomey Gap for the evolutionary history of the West African forest faunas. It also has conservation implications given that the new species is one of the main targets of the local bushmeat trade.
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Distinct population structure in a phenotypically homogeneous rock-dwelling cichlid fish from Lake Tanganyika.
- Several lineages of cichlid fishes in the East African Great Lakes display stunning levels of morphological diversification. The rapid evolution of rock-dwelling polygynous mouthbrooders in Lake Malawi, for example, was in part ascribed to their allopatric distribution on disjunct stretches of rocky coast, where even short habitat discontinuities reduce gene flow effectively. However, as seen in other cichlids, ecological barriers do not always prevent gene flow, whereas genetic structure can develop along continuous habitat, and morphological diversification does not necessarily accompany genetic differentiation. The present study investigates the population structure of Variabilichromis moorii, a monogamous substrate-brooding lamprologine of rocky coasts in Lake Tanganyika, which occurs over about 1000 km of shoreline almost without phenotypic variation. Phylogeographic analyses of mitochondrial DNA sequences indicated that dispersal is infrequent and generally occurs between adjacent locations only. Exceptions to this pattern are closely related haplotypes from certain locations on opposite lakeshores, a phenomenon which has been observed in other species and is thought to reflect lake crossing along an underwater ridge in times of low water level. Genetic population differentiation, estimated from mitochondrial DNA and microsatellite data in six adjacent populations, was equally high across localities separated by sandy shores and along uninterrupted stretches of rocky shore. Our results suggest that ecological barriers are not required to induce philopatric behavior in Variabilichromis, and that morphological stasis persists in the face of high levels of neutral genetic differentiation.
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Divergent and reticulate processes in evolution of Ethiopian Lophuromys flavopunctatus species complex : evidence from mitochondrial and nuclear DNA differentiation patterns
- Molecular study of mitochondrial and nuclear genes and cytogenetic analysis were performed to examine possible patterns of speciation in the diverse Lophuromys flavopunctatus species complex of Ethiopia. Phylogenetic analysis of mtDNA data resulted in an unresolved bush of ten deeply diverged haplotype groups corresponding to potential species either well supported by various types of character or ‘cryptic’. The cytogenetic analysis showed represen- tatives of five of these mtDNA lineages to share an identical karyotype (2n = 70, NFa = 84), that has not been found previously in Ethiopia. One of them, L. cf. sikapusi, being a member of the L. flavopunctatus species complex, dem- onstrates remarkable morphological similarity to representatives of another species complex, L. sikapusi s.l., which might be considered as a result of convergent evolution in analogous environments. Analysis of RAPD data suggests that at least two mtDNA types might have been subject to interspecific transfer due to hybridization. In the case of two sympatric haplotypes of L. brunneus we may assume that the contemporary pattern of variation between them can be explained by relatively recent hybridization with another distinct species, L. flavopunctatus. The formation of two groups belonging to distinct mitochondrial lineages within northern populations could be associated with more complex processes including ancient hybridization.
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Diversity, dynamics and reproduction in a community of small mammals in Upper Guinea , with emphasis on pygmy mice ecology
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DNA Barcoding Amphibians and Reptiles
- Only a few major research programs are currently targeting COI barcoding of amphibians and reptiles (including chelonians and crocodiles), two major groups of tetrapods. Amphibian and reptile species are typically old, strongly divergent, and contain deep conspecifi c lineages which might lead to problems in species assignment with incomplete reference databases. As far as known, there is no single pair of COI primers that will guarantee a suffi cient rate of success across all amphibian and reptile taxa, or within major subclades of amphibians and reptiles, which means that the PCR amplifi cation strategy needs to be adjusted depending on the specifi c research question. In general, many more amphibian and reptile taxa have been sequenced for 16S rDNA, which for some purposes may be a suitable complementary marker, at least until a more comprehensive COI reference database becomes available. DNA barcoding has successfully been used to identify amphibian larval stages (tadpoles) in species-rich tropical assemblages. Tissue sampling, DNA extraction, and amplifi cation of COI is straightforward in amphibians and reptiles. Single primer pairs are likely to have a failure rate between 5 and 50\% if taxa of a wide taxonomic range are targeted; in such cases the use of primer cocktails or subsequent hierarchical usage of different primer pairs is necessary. If the target group is taxonomically limited, many studies have followed a strategy of designing specifi c primers which then allow an easy and reliable amplifi cation of all samples.
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Effect of pH on the biological availability of copper to the brine shrimp Artemia franciscana
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Enzyme variation in Haplochromine cichlid fishes from Lake Victoria
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Etude préliminaire des effets de la fragmentation des forêts sur la similarité des habitats et leurs richesses en espèces de rongeurs (Masako, RD Congo).
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Evaluation of microwave heating digestion and graphite furnace atomic absorption spectrometry with continuum source background correction for the determination of iron, copper and cadmium in brine shrimp
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Evolution of the tribe Tropheini from Lake Tanganyika: synchronized explosive speciation producing multiple evolutionary parallelism
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Evolutionary relationships among narrow-headed rats (genus Stenocephalemys, muridae, rodentia) inferred from complete cytochrome b gene sequences
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Extensive Introgression among Ancestral mtDNA Lineages: Phylogenetic Relationships of the Utaka within the Lake Malawi Cichlid Flock.
- We present a comprehensive phylogenetic analysis of the Utaka, an informal taxonomic group of cichlid species from Lake Malawi. We analyse both nuclear and mtDNA data from five Utaka species representing two (Copadichromis and Mchenga) of the three genera within Utaka. Within three of the five analysed species we find two very divergent mtDNA lineages. These lineages are widespread and occur sympatrically in conspecific individuals in different areas throughout the lake. In a broader taxonomic context including representatives of the main groups within the Lake Malawi cichlid fauna, we find that one of these lineages clusters within the non-Mbuna mtDNA clade, while the other forms a separate clade stemming from the base of the Malawian cichlid radiation. This second mtDNA lineage was only found in Utaka individuals, mostly within Copadichromis sp. "virginalis kajose" specimens. The nuclear genes analysed, on the other hand, did not show traces of divergence within each species. We suggest that the discrepancy between the mtDNA and the nuclear DNA signatures is best explained by a past hybridisation event by which the mtDNA of another species introgressed into the ancestral Copadichromis sp. "virginalis kajose" gene pool.
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From conical to spatulate: Intra-and interspecific changes in tooth shape in closely related cichlids (Teleostei; Cichlidae: Eretmodini)
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General protein patterns of muscle homogenates of some Lake Victoria haplochromines (Pisces: Cichlidae)
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Genetic diversity and condition factor: a significant relationship in Flemish but not in German populations of the European bullhead (Cottus gobio L.).
- Although evidence of associations between genetic diversity and fitness in wild species has been published, the lack of a comprehensive review across species and the existence of contradictory results have led to scepticism remaining about its existence and importance in natural populations. In this study, the relationship between genetic diversity at six microsatellite loci and condition factor (a fitness related trait) was investigated at the population level in both Flemish and German populations of the European bullhead (Cottus gobio). A significant positive correlation was observed between genetic variability and the condition factor in Flemish but not in German bullhead populations. Environmental conditions such as conductivity of the water seemed more important in determining the condition factor of these latter populations. Regardless of the underlying mechanism(s) responsible for the different relationships, the results of this study suggest that both genetic and environmental variables can influence condition factor of bullhead populations.
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Genetics and speciation in African lacustrine cichlids
